1. Field of the Invention
The present invention relates to an apparatus for sensing a biomolecule or a chemical material, and more particularly, to a sensing switch that physically moves due to an electrostatic force between an electrode having the same polarity as a ligand and another electrode having the opposite polarity to the ligand or due to a magnetic force between a magnetic bead bound to a ligand and a magnetic field generation device, thus acting as a switch, and a sensing method using the same.
2. Description of the Related Art
Effective sensing of biomolecules and chemical materials is required in a wide range of applications, such as biochips. A biochip is formed by immobilizing a receptor (biomolecules), such as DNA or a protein, with high density on a support, and can be used to analyze gene expression characteristics, gene defects, protein distribution, reaction characteristics, and the like. Biochips are categorized into microarray chips and lab-on-a-chips according to where a receptor is affixed. A microarray chip is formed by affixing a receptor to a solid support, and a lab-on-a-chip is formed by affixing a receptor to a microchannel. In order to find a target material in a sample able to bind to a receptor immobilized on a support, the biochip requires a system that can detect whether a receptor immobilized on a support.
In general, a DNA chip for gene analysis is used to analyze a gene by labeling a sample DNA with a fluorescent pigment, reacting the labeled sample DNA with a receptor on the chip, and detecting the fluorescent material remaining on the surface of the chip using a confocal microscope and a CCD camera (See U.S. Pat. No. 6,141,086). However, it is difficult to miniaturize the equipment required for such an optical sensing method and the result cannot be digitally output. Therefore, much research has been conducted to develop a new method in which the analysis result can be output via an electrical signal.
A method of and apparatuses for electrochemically detecting DNA hybridization using a metal compound, which can be easily oxidized and reduced, has been researched in many labs including a Clinical Micro Sensor (See U.S. Pat. Nos. 6,096,273 and 6,090,933). In this case, when DNA is hybridized, another compound containing a metal that can be easily oxidized and reduced is combined with the hybridized DNA to form a complex, which is electrochemically detected [Anal. Chem., Vol. 70, pp. 4670-4677, 1998; J. Am. Chem. Soc., Vol. 119, pp. 9861-9870, 1997; Analytica Chimica Acta, Vol. 286, pp.219-224, 1994; and Bioconjugate Chem., Vol. 8, pp. 906-913, 1997.] However, the electrochemical methods also require a labeling process.
In addition, a conventional fluorescent or electrochemical sensing method requires a sensor, a measuring apparatus for measuring the output of the sensor, and an analysis device for processing a signal obtained from the measuring apparatus. Therefore, the entire system is bulky, many expensive apparatuses are required, and skilled engineers are required to perform each operation. Even when all these requirements are complied with, it takes a long time to obtain a final result and a noise is guaranteed in connections between apparatuses.
In order to overcome these problems, the inventors of the present invention confirmed that a sensor can physically moves due to an electrostatic force between an electrode having the same polarity as a ligand and another electrode having an opposite polarity to the ligand or due to a magnetic force between a magnetic bead bound to a ligand and a magnetic field generation device, thus acting as a switch, so that a miniaturized sensing switch that needs not require signal processing can be manufactured.